a) `x. (x + 7) = 0`
`⇒` \(\left[ \begin{array}{l}x=0\\x + 7=0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x=0\\x = -7\end{array} \right.\)
b) `(x + 12). (x - 3) = 0`
`⇒` \(\left[ \begin{array}{l}x + 12=0\\x - 3= 0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x=-12\\x = 3\end{array} \right.\)
c) `(-x + 5). (3 - x) = 0`
`⇒` \(\left[ \begin{array}{l}-x + 5=0\\3 - x = 0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}-x = -5\\x = 3\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x= 5\\x = 3\end{array} \right.\)
d) `x. (2 + x). (7 - x) = 0`
`⇒` \(\left[ \begin{array}{l}x=0\\2 + x = 0\\7 - x = 0 \end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x=0\\x= -2\\ x = 7\end{array} \right.\)
e) `(x - 1). (x + 2). (-x - 3) = 0`
`⇒` \(\left[ \begin{array}{l}x- 1=0\\x + 2 = 0\\-x - 3 = 0 \end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 1\\x = -2\\-x = 3\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 1\\x = -2\\x = -3\end{array} \right.\)
